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HUMAN CENTRIC LIGHTING
Whitepaper
“Following extensive studies, human-centric lighting
installations are emerging as a way to meet people’s emotional
needs purely through the control of LED’s illuminance levels,
colour temperature and direction of light.”
Henri Juslén D.Sc. (Tech.), Director, Product portfolio
management
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Introduction
Lighting technologies continue to evolve and improve, bringing a
range of benefits to commercial building specifiers and
end-users.
These include better energy efficiency and greater freedom and
flexibility in how lighting is applied and controlled in the
workspace.
At the same time, there is a growing body of research and
information available on the impact of lighting on human beings,
with particular resonance on its effect upon our emotions, our
well-being and our workplace productivity.
This white paper explores the connections between these two
trends and the potential for a more widespread adoption of human
centric lighting in commercial building environments.
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What is Human Centric Lighting?
Human centric lighting is the means by which the emotional
wellbeing, comfort, health and, indeed, productivity of individuals
can be improved simply through the correct control of the lighting
in place.
Our thinking behind human centric lighting is defined by
research carried out over the last quarter century.
In the early 1990’s, scientists started to study the efficacy of
light therapy in the treatment of seasonal affective disorder
(SAD). Michael Terman et al (1989) first noted the anti-depressant
impact of bright, artificial light on SAD patients. Since this
time, many researchers have replicated these findings.
It is clear then that with the reduction in daylight hours
during the winter, we are subjected to longer periods of biological
darkness for large parts of the day, and with this change in the
seasons comes a lack of energy, low mood and irritability.
For example, about 20% of the UK population find themselves
suffering from the symptoms of seasonal affective disorder. In 2%
of the population, sufferers of SAD can suffer even more
debilitating issues, and cannot function normally without
appropriate treatment.
To counter the negative effects of SAD, it is important for
sufferers to receive as much exposure to daylight as possible.
Studies have found that the natural colour of daylight
stimulates the production of melatonin and serotonin which control
the physical, mental and behavioural changes that follow a roughly
24-hour cycle, responding primarily to light and darkness in a
person, or their circadian rhythm.
Obtaining a sufficient level of light exposure can be difficult
during winter. However, without the required amounts of melatonin
and serotonin in the human brain, people are much more likely to be
affected by fatigue and even depression.
SAD can be effectively treated by light therapy.
Light levels are raised significantly, particularly in the
morning, to help alleviate the disruption of the circadian rhythm,
caused by the reduced amount of natural light. Michael Terman et al
discovered that there was a clear positive treatment effect for
early morning bright light exposure and similar results for midday
and evening exposure.
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More recently, other issues have been raised concerning the
human body directly. It was found that in addition to rod and cone
cells, the eye also contains other light sensitive receptors and
these are linked with mental alertness. Studies showed that the
spectral sensitivity of these receptors were different to that of
cone cells: the sensitivity curve of cone cells peaks at yellowish
light at 555nm, whereas the peak sensitivity of the previously
undiscovered receptors seemed to be in the bluer, colder light at
about 470nm.
In practice, this means that our alertness responds not only to
the intensity of light but also to the colour temperature. From
this research, we now know that exposure to light can increase
alertness much quicker too. Of course, this makes sense when you
consider the variations we experience in natural daylight. It
changes in terms of both intensity and colour temperature, not only
over the course of the day but also as the seasons change.
Bearing this in mind, it has become apparent that the direction
of light, colour temperature and overall illuminance levels in a
space can have a notable effect on a person’s mood. The natural
circadian rhythm of a person can be supported by using warmer
(relaxing) light with lower intensity in the morning and evenings,
and cooler (energising) light during a typical working day.
In essence, if we can control the lighting in our buildings
better, then we can create a human centric lighting solution.
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What is lighting control?
The term lighting control is often used to describe stand-alone
control of the lighting within a space.
An automated lighting control system is an intelligent
network-based solution that incorporates communication between
various inputs and outputs with the use of one or more central
computing devices. These devices may include relays, occupancy
sensors, switches or touchscreens, and signals from other building
systems, such as, heating, ventilation and air-conditioning
systems. Adjustment of the system occurs both at device locations
and at central computer locations via software programs or other
interface devices.
Lighting control systems are widely used on both indoor and
outdoor lighting of commercial buildings to provide the right
amount of light where and when it is needed. This type of system is
often used to maximise energy savings and comply with relevant
building regulations in specific countries.
Colour temperature is a fairly new, yet important facet of
lighting control solutions within buildings. The colour temperature
depicts the temperature of an ideal black-body radiator that
radiates light of comparable hue to that of the source.
In other words, it can tell you whether the light emitted is
going to be a warm yellowy tone or a cool blue white colour. This
can be denoted by the Kelvin scale, lights with a rating of 5000K
or lower are typically the warmer tones, whereas those above 5000K
are the crisp, cool whites.
FLEXIBLE
Design lighting just the way you want
SCALABLE
From small standalone solutions to large lighting
networks
EASY
Easy and cost-efficient set up
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Lighting Control Standards
One of the most popular standards available for lighting control
is DALI.
DALI has recently updated its standard to offer support for
colour control, covering both RGB and colour temperature. This
increased colour control gives architects many more options in how
they can control the warmth of the light in each room of a building
using DALI fixtures.
By using an effective lighting control system, spaces can be
created with multiple uses and properties. Automated dimming and
colour control can be used to change the mood of a room and the
dynamics of a zone or group of zones according to purpose, time of
day, natural daylight, occupancy or other factors. Such controls
are also capable of significantly reducing the lighting system’s
energy consumption.
At the heart of lighting control thinking and practice is DALI.
First drafted as a standard in 2000, DALI is a data protocol and
transport mechanism that was jointly developed and specified by
several manufacturers of lighting equipment.
DALI lamp fixtures are intelligent, 100% dimmable and can all be
controlled, monitored and maintained using this two wire global IEC
62386 open standards communication protocol. A wide variety of
fixtures are manufactured globally by manufacturers in line with
DALI, including LED, fluorescent, HID, halogen, incandescent and
emergency lighting, low voltage transformers, PE cells, motion
detectors, wall switches and gateways to other protocols.
Up to 64 individually addressed DALI light fixtures may be
connected on a single and simple two wire network to be
communicated with individually, collectively or in groups. These
DALI fixtures can then be instructed, by sending commands along the
two wire network, to turn ON, OFF, Dim Up, Dim down. Additional
operational status information is available from each DALI fixture,
confirming its ability to operate effectively or to confirm a fault
condition.
The key thinking behind the DALI standard was interoperability.
The common platform of DALI enables equipment from different
manufacturers to be connected together, giving designers a ‘best of
breed’ competitive choice in performance and style of lighting
solution for their particular building. This gives specifiers
considerable flexibility where cost per square metre, functionality
and form factor can often be determining factors on equipment
selection.
Overall light levels should also be considered – a DALI control
system can be programmed to increase or decrease lighting levels
according to exterior lighting. As such, a typical system may see
illuminance levels needing to be set higher or lower at certain
times of the day – during the morning and towards the end of the
day, lighting levels may need to be increased, according to ambient
lighting conditions.
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Lighting Technology Evolution
Luminaire manufacturers now produce lighting fixtures with
adjustable colour temperatures.
At first, these luminaires consisted of multiple fluorescent
tubes of different colour temperatures, mixed at a desired ratio.
This approach required two controllable ballasts per luminaire.
Now, tunable LED lighting has progressed to almost mainstream
technology. By adjusting the relative intensities of warm and cool
LEDs, end users can change the colour temperature of the
device.
The thickness of the phosphor layer in the LED, together with
the wavelength of the blue chip, influence what the colour
temperature of the LED will be. The colour temperature of a light
source is measured in Kelvins (K). Light with a temperature over
5,000K is typically known as cool colour lighting, with a bluish
white appearance. Lower colour temperatures of between 2700K-3000K
are warm colours, with a more yellowish white appearance.
Using this technology has allowed for lighting to be programmed
at the same warmth as daylight, with natural highs and lows as the
day progresses. These advances have meant that the artificial
lighting in offices, schools, shopping centres and homes can be as
close to natural light as possible, making the effects of human
centric lighting highly effective.
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What is Good Human Centric Lighting?
Light is the synchronising pulse generator for our circadian
rhythm.
Powerful bluish morning light suppresses the production of
Melatonin (natural soporific) thus supporting the production of
Cortisol (stress hormone), allowing you to be alert, active and
ready for the working day, and Serotonin, which elevates your mood.
Warm, cosy light in the evening releases the production of
Melatonin (natural soporific), which leaves you feeling relaxed and
sleepy.
We can incorporate lighting controls to benefit the occupant of
a building, as well as just the
property itself. This can be achieved by ensuring that the light
levels being controlled are those that will aid productivity when
needed, and create a calm entertaining space at other times.
Creating these different atmospheres can also look to aid
sleeping patterns in the home by
creating the right ambience to fall asleep, and to wake up,
making individuals feel more energised and
refreshed during the day.
Human centric lighting is used to benefits those in several
different applications.
These include Healthcare, Education, Workplaces, Industrial,
Retail, Hospitality and Residential.
In healthcare, patients can experience enhanced medicated
efficacy, reduced therapy periods and capacity requirements and
stimulation by light despite outdoor conditions.
In education, it increases concentration and decreases fatigue.
In the work place, it there has been found to be individualised
maximisation of concentration and energy, increased employee
motivation and commitment, as well as increase in work performance,
alertness, and employee satisfaction.
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In industrial settings, it helps with biorhythm adjustment for
nightshift workers, improved output and error rate of repetitive
work steps.
For retail, the increase in awareness levels was most important.
Daylight compatible product presentations were possible, as well as
staging of Point of Sale products with different colour
temperatures and RGB.
Extended daytime in shopping malls was possible, in addition to
zoning of shops through different lighting set ups, seasonal
lighting stimulation and creating a feel good atmosphere.
These all allow for huge flexibility in changing a retails
space’s ambiance, without any alterations to the building.
Hospitality buildings saw support for wellbeing of guests, and
bedrooms and in dining areas.
This increased value and comfort of these establishments.
Similarly to retail, human centric lighting provides flexibility in
lighting for different needs, such as transforming a dining room
from
bright and airy for breakfast, to relaxed for dinner and the use
of colour allows for accentuation of architecture
and design, and impact for events.
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SummaryThe ability to control light colour temperature with
predefined rhythms gives interesting and new opportunities to
implement lighting designs with high energy efficiency, which can
boost the well-being of occupants and also provide many benefits
when applied in different environments.
Human centric lighting is an emerging methodology where there
are multiple options for implementation, usage and management of
the solution. Working with a lighting control specialist, lighting
designers, specifiers and end users can be guided accordingly to
ensure the selected system meets the needs of the environment in
which it will be installed.
By ensuring that lighting is human centric, we can enhance a
user’s day to day mood, wellbeing, productivity and attention
levels. As we have seen, these benefits spread across a wide range
of applications, from schools and offices, to retail and industrial
applications.
If we implement the concept of human centric lighting across a
broad range of applications then we will help to get the best out
of people and particularly improve the quality of life for SAD
sufferers.
Improved levels of productivity and concentration in education
and the workplace can only be a good thing as it will aid
development in industry and business for many years to come.
Equally, in retail, more focussed and attentive shoppers will lead
to more sales and a boost in economy.
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References:
Henri Juslén (2007) Lighting, Productivity and Preferred
Illuminances – Field Studies in the Industrial Environment
http://lib.tkk.fi/Diss/2007/isbn9789512289622/
Juslén HT, Tenner AD. (2005) Mechanisms involved in enhancing
human performance by changing the lighting in the industrial
workplace. International Journal of Industrial Ergonomics. 35,
843-855. © 2005 Elsevier Science. By permission.
http://lib.tkk.fi/Diss/2007/isbn9789512289622/article1.pdf
Juslén HT, Tenner AD. (2007) The use of task lighting in an
industrial work area provided with daylight. Journal of Light &
Visual Environment. 31, 1, 25-31. © 2007 Illuminating Engineering
Institute of Japan (IEIJ). By permission.
http://lib.tkk.fi/Diss/2007/isbn9789512289622/article6.pdf
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